Some popular greenhouse crops have a long history of proven light deprivation treatment, while others are completely unknown. It’s best to start with at least one plant known to respond well to light dep before investing in a full-size greenhouse. If you’re still experimenting with your current crops to see what benefits from this technique, try a smaller tent or enclosure made from BTL Liners light-blocking cover. Then, you can expand from these common plants grown in light dep greenhouses to find new crops that flourish during longer nights.
Strawberries
Strawberries are one of the few edible greenhouse crops to benefit from light deprivation. While many crops benefit from extended days through the use of artificial lighting, few of them grow better or fruit faster when exposed to longer nights. Short day strawberries need long nights to trigger fruiting, so they obviously benefit from light deprivation and photoperiod manipulation. It’s often possible to make these varieties fruit multiple times a year by heavily manipulating the photoperiods. Of course, everbearing strawberry varieties also respond similarly since they’re designed to fruit during multiple seasons anyway. Everbearing strawberries can truly live up to their name when grown in a light dep greenhouse with intensive management.
Chrysanthemums
Mums are some of the most light sensitive plants commonly sold as bedding annuals. While they’re usually purchased in mid-to-late summer to refresh the landscape for autumn, they also prefer not to bloom until nights are between 10.5 and 12 hours long. In most parts of the Northern Hemisphere, this is later and colder than the plants will survive outdoors. Growers work around these seasonal incompatibilities with the power of light deprivation. By keeping the mums in the dark for longer periods, it’s possible to get them budding and blooming as early as desired in the year. Since millions of mums are sold each year, that translates into thousands of light deprivation greenhouses to keep them all flowering on schedule.
Asters and Zinnias
When it comes to cut and bedding flowers, both asters and zinnias respond well to light deprivation. As with chrysanthemums, the technique is primarily used for triggering budding and flowering. Zinnias and dahlias can both grow too quickly in the warm environment of a well-lit greenhouse, so these plants are often stunted slightly with light deprivation to keep them compact until it’s time to bloom. Other types of asters and cone flowers like echinacea are also triggered to bloom year-round for harvesting to transform into herbal teas and other products.
Poinsettias
Poinsettias are commonly referred to as holiday or Christmas flowers, but they’re technically just sporting brightly colored foliage. Yet, that foliage won’t change into brilliant red, pink, white, or lime green until long nights begin signaling it’s the right time of year. This leaves poinsettias naturally changing color a little too late to appreciate in the winter. Light deprivation is the only way to commercially produce poinsettias that match up with holiday demand, especially in the Southern hemisphere. Poinsettias need complete blackout conditions for at least 12 to 14 hours a day to trigger the color change, so a few mistakes in light deprivation cover could result in extensive losses during the growing season.
Christmas Cactus and Easter Lilies
Most blooming succulents, including Christmas cactus and kalanchoe, require extended periods of darkness to trigger flowering. On the other end, Easter lilies bloom as days start to lengthen and may need supplemental light instead. Light deprivation is required either way, whether it’s used for triggering the emergence of flowers or keeping them from budding too early.
Begonias
Begonias are some of the most collected and valuable houseplants, and they’re known for needing long nights to trigger their rare flowering habits. Flowering begonias are much more attractive to consumers, but trying to coax a rex begonia to bloom can seem impossible in a commercial greenhouse setting. Light deprivation is essential to induce flowering from these sensitive plants, yet only the highest quality covers will work since they’re so sensitive to fluctuations in temperature and humidity.
These are just a few of the dozens of plants commonly manipulated with light deprivation. Cosmos, petunias, salvias, snapdragons, marigolds, and sunflowers are other good options for controlling in this way. With further experimentation and testing, new opportunities are sure to be found in the next few years. Start your own tests on greenhouse crops by ordering reliable light deprivation materials from BTL Liners.
